Pyrobitumen is a solid, black, bituminous material which is found in significant quantities in certain subterranean, hydrocarbon-containing reservoirs.
The reservoirs are carbonate reservoirs and some sandstone reservoirs.
The reservoirs which we have examined typically contain between 0.1 wt. % and 10 wt. % pyrobitumen.
The pyrobitumen is typically present as a filling or lining within vugular and intercrystalline pore networks and fractures. It is generally accepted that pyrobitumen was formed in-situ by either thermal alteration of oil or deasphalting of heavy oil.
The pyrobitumen is an impediment to hydrocarbon productivity because of its oil-wetness, porosity occlusion and permeability reduction characteristics.
It is the objective of the present invention to improve the effective permeability of the reservoir rock and enhance the producibility of a well completed in the reservoir, by removing pyrobitumen.